Field of the Invention
Embodiments of the present invention relates to the art of a control system for a hybrid vehicle having different kinds of prime movers such as an internal combustion engine and a motor, and especially to a control system for controlling a braking force established by the prime mover.
Discussion of the Related Art
JP-A-2013-129380 describes a hybrid vehicle in which a motor-generator establishes a braking force instead of an engine. The hybrid vehicle taught by JP-A-2013-129380 is provided with the engine, a first motor-generator that can control a speed of the engine, and a second motor-generator that can adjust an output torque. According to the teachings of JP-A-2013-129380, a control system is configured to operate the second motor-generator as a generator to establish a braking force when an accelerator pedal is returned to decelerate the vehicle. In addition, the control system is further configured to consume an electric power generated by the second motor-generator by cranking the engine by the first motor-generator if a battery is charged overly during establishing the braking force by the second motor-generator.
That is, according to the teachings of JP-A-2013-129380, the electric power generated by the second motor-generator is entirely stored into the battery during establishing the braking force by the second motor-generator, and hence the battery is fully charged frequently if the vehicle is decelerated frequently. As described, the control system taught by JP-A-2013-129380 carries out a cranking of the engine by the first motor-generator if the battery is fully charged. For this reason, the engine is activated frequently and hence a driver may feel discomfort.